Metal interconnection structure and method for forming metal interlayer via and metal interconnection line

A method for forming a metal interconnection line, comprising:

• forming a conductive barrier layer and a seed layer on a first dielectric layer and a first metal layer embedded in the first dielectric layer;
• forming a mask pattern on the seed layer to expose a portion of the seed layer covering at least the first metal layer;
• growing a second metal layer on the exposed portion of the seed layer;
• removing the mask pattern and also a portion of the conductive barrier layer and a portion of the seed layer carrying the mask pattern to expose side walls of the second metal layer and the first dielectric layer;
• forming a barrier layer only on the side walls.

A method for forming a metal interconnection line, comprising:

• forming a conductive barrier layer and a seed layer on a first dielectric layer and a first metal layer embedded in the first dielectric layer;
• forming a mask pattern on the seed layer to expose a portion of the seed layer covering at least the first metal layer;
• growing a second metal layer on the exposed portion of the seed layer;
• removing the mask pattern and also a portion of the conductive barrier layer and a portion of the seed layer carrying the mask pattern to expose side walls of the second metal layer and the first dielectric layer;
• forming an insulating barrier layer on the side walls and on the first dielectric layer.